1. Field of the Invention
The present invention relates to a torsional damper device, inter alia for automobile vehicle clutch disks, comprising two coaxial parts disposed to rotate relative to one another within defined limits of relative angular movement and of which one comprises a hub flange and the other comprises two guide rings disposed one on each side of the hub flange, elastic means disposed circumferentially between the coaxial parts and accommodated in openings in the hub flange and in each of the guide rings, and friction means disposed axially between said coaxial parts, said friction means comprising a pressure ring inserted between the hub flange and a first guide ring and having on both sides respective annular friction surfaces.
2. Description of the Prior Art
This type of torsional damper device is normally incorporated in the design of a clutch disk, particularly for automobile vehicles, the hub flange being, in a first type of embodiment, associated with a hub which is designed to be constrained to rotate with a driven shaft, the primary shaft of the automobile vehicle gearbox, for example, whereas one of the guide rings receives a fixed facing carrier which is designed to be coupled to the driving shaft of the automobile vehicle when the clutch is engaged. Alternatively, the hub flange has the facing carrier fixed to it whereas the guide rings are associated with the hub.
The effect of the various friction means operative between the two coaxial parts of the torsional damger device is to introduce a hysteresis effect into the operating characteristics of the device, that is to say to introduce a difference, for a given value of relative angular movement between the coaxial parts of said device, between, on the one hand, the value of the torque transmitted from one of these coaxial parts to the other when the hrelative angular displacement is increasing and, on the other hand, the value of this torque when the relative angular disiplacement is decreasing.
These various friction means further have the effect, when torque is being transmitted, of producing between the coaxial parts of the device friction which is directly proportional to the displacement of the device away from its rest position corresponding to transmission of a null torque.
However beneficial they may be, these various friction means significantly increase the overall size of the torsional damper device, in particular the axial dimension, and do not procure as accurate a value of friction as might be wished.
An object of the present invention is a torsional damper device, inter alia for automobile vehicle clutch disks, of the type indicated hereinabove the operation of which is particularly efficient and which features all desirable characteristics for both direct and retrograde transmission of the torque, with reduced overall size, especially the axial dimension, and a simple and strong structure.
Another object of the invention is a torsional damper device of the type considered in which, with a very simple structure, the magnitude of the friction is adapted to vary according to the relative angular position of the two coaxial parts of the device, with high accuracy.